Hufnagel Equal-Area Pseudocylindrical Map Projection Family

In 1989, Herbert Hufnagel introduced a generalization of the Mollweide projection, resulting in a family of pseudocylindrical equal-area projections. The Mollweide, Eckert Ⅳ and Wagner Ⅳ projections are members of this family.
All projections are equal-area. Some parameter combinations create folding graticules.